Introduction to Programming

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# Introduction to Programming - PowerPoint PPT Presentation

Introduction to Programming. Java Lab 3: Variables and Number types. JavaLab3 lecture slides.ppt Ping Brennan ( Ping.Brennan@gmail.com ). 24 January 2014. Java Project. Project Name : JavaLab3. ExerciseWithIntegers. OrderPrice. SeparateDigits. Class ExerciseWithIntegers. Objectives

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## Introduction to Programming

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### Introduction to Programming

Java Lab 3:

Variables and Number types

JavaLab3 lecture slides.ppt

Ping Brennan (Ping.Brennan@gmail.com)

24 January 2014

Java Project

Project Name: JavaLab3

ExerciseWithIntegers

OrderPrice

SeparateDigits

Class ExerciseWithIntegers
• Objectives
• Perform integer calculations using the arithmetic operators and Math methods.
• Understanding integer as a data type.
• Computation

Math.abs(x), Math.min(a, b), Math.max(a, b)

where x, a, b, are integers (or expressions) of type int.

• Data type

integer range -231 to 231-1

i.e. -2147483648 ... 2147483647

• Applying
• Read keyboard input using Scanner class
Anatomy of Class ExerciseWithIntegers

import java.util.Scanner; // first line in the program

public class ExerciseWithIntegers

{

public static void main(String[]args)

{

// create a Scanner object in to read keyboard input

Scanner in = new Scanner(System.in);

System.out.print("Enter two integers: "); // prompt user to input

intnum1 = in.nextInt(); // reads in first integer input

/* Write code similar to the above statement to declare a new

variable num2 of type int to read in the second integer input. */

/* Next write separate Java statements to print:

the sum, the difference, the product, the average, the absolute

value of the difference, the maximum and the minimum. */

}

}

Tip: use the methods Math.abs(x), Math.min(a, b) and Math.max(a, b) from the Math class (java.lang.Math)

Class OrderPrice
• Calculates the price of an order from the total price and number of books ordered.
• Objectives
• Using arithmetic operators : + , – , * , /
• Understanding arithmetic expressions
• Formulae
• Applying
• Read keyboard input using Scanner class
• Declaring variables of data types: int and double

tax = totalBookPrice * 0.075;

shippingCharge = noOfBooks * 2.00;

orderPrice= totalBookPrice + tax + shippingCharge;

Anatomy of Class OrderPrice

import java.util.Scanner; // first line in the program

public class OrderPrice

{

public static void main(String[] args)

{

// Write separate Java statements to do the following:

// a) Read in the total book price and the number of books

// b) Compute the tax (i.e. 7.5% of the total book price)

// c) Compute the shipping charge (\$2 per book)

// d) Price of order = total book price + tax + shipping charge

// e) Print the price of the order

}

}

Class SeparateDigits
• Reads in a five digit positive integer and prints out the individual digits, separated by spaces. For example, the input 16348 is printed out as: 1 6 3 4 8
• Objective
• Understand the arithmetic operators: % (modulus) and

/ (division).

• Formulae
• Applying
• Read input using Scanner class

tenThousand = posNumber/10000;

thousand = (posNumber% 10000) / 1000;

hundred = (posNumber% 1000) / 100;

// continue to write own formulae to calculate ten and unit

Anatomy of Class SeparateDigits

import java.util.Scanner; // first line in the program

public class SeparateDigits

{

public static void main(String[] args)

{

/* Declare a variable posNumber of type int and store

a five digit positive number input in the variable. */

// firstly declare all relevant variables below before using them.

tenThousand = posNumber/10000;

thousand = (posNumber% 10000) / 1000;

hundred = (posNumber% 1000) / 100;

// write Java statements to calculate ten and unit

// write code to print out the individual digits, separated by spaces

}

}